Ms ACCESS and queries: dates in graph not in order

I use queries in Ms ACCESS to create graphs (shown in forms) to represent monthly spend data on a supplier. I want the x axis to be the months in chronological order, and this is where I'm having issues.

The picture above shows that the x axis starts with april 2016, although the earliest date is august 2015.

[Item Master] is the table were all data is retrieved from. DateStamp refers to the column with months, SpendPerMaterial is the spend of a certain material in that month (which is aggregated since we look at the supplier level, not the material level), and List0 is a list where users can select a supplier from a list of suppliers.